Prosecutors placed French far-right leader Marine Le Pen under formal investigation on Friday as part of a probe into the alleged misuse of European Union funds to pay parliamentary assistants.

Le Pen, who is being investigated for breach of trust, has previously denied any wrongdoing in a case that she has said is politically motivated.

In a statement, her lawyer said she would launch an appeal against the investigation.

The case relates to an amount of about 5 million euros ($5.71 million).

It was announced Le Pen had been placed under formal investigation after she appeared before judges on Friday. She had been summoned previously, but refused to go during her campaign bid for the French presidency.

The European Parliament believes the money went to National Front employees working for the party in France rather than those working for the party's lawmakers in Brussels.

The formal investigation comes less than two weeks after Le Pen won a seat in theFrench National Assembly. She is no longer a member of the European Parliament.

Le Pen also faces an investigation into the financing of past election campaigns and a probe into her tweeting of pictures of Islamic State violence.